The invention relates to relates to an arrangement for dental imaging having an intraoral sensor, which receives radiation at the moment of exposure for providing image data.
In digital intraoral imaging, different positioning of a sensor is required depending on the imaging area and/or clinical needs (i.e. molar, premolar, bitewing images, etc.). Currently, the exposed image is rotated to the right orientation in the image processing software or the viewing software. The software has a feature where the user can select the orientation through the user interface before exposing the image. The prior art embodiments require user intervention to get the image rotated into the right orientation.
It is an objective of the present invention to provide an arrangement for dental imaging having intraoral sensor, which makes it possible to automatically display the image always in the right orientation. According to this invention, an intraoral sensor is provided, which receives radiation at the moment of exposure for providing image data, said intraoral sensor comprising                a housing, which encloses a detector and electronics,        an orientation position sensor, which senses orientation of the intraoral sensor at the moment of exposure to provide orientation information,        said arrangement for dental imaging further comprising        a display unit for displaying image data and data transfer elements, which are connected to the detector and electronics for transmitting the image data and orientation information to the display unit, and        said display unit having coupled therewith image processing software, which processes the image data and utilizes the orientation information relevant to the image data for having an image to be presented on a display unit shown the right way.        
In one of the preferred embodiments of the invention, the image processing software includes a pattern recognition algorithm, which enables pinpointing a tooth in question, based on the orientation information supplied by the orientation sensor and sensor location information determined on the basis of that.
The orientation sensor used in an intraoral sensor of the invention can be a small-size gravity sensor, such as e.g. a VTI Technologies SCA 1000 series accelerometer and/or a compass circuit, such as e.g. a Philips Semiconductors KMZ41 circuit, which both can be placed in a sensor housing. These sensors are micromachined (MEMS) components which are handled the same way as CMOS/CCD chips. Installation of an orientation sensor in the intraoral sensor is a reasonably straightforward procedure.
The inventive solution enables the use of angle information for correcting perspective errors of the image by making use of orientation information regarding the orientation sensor and possibly the tube head.
Among others, the invention provides benefits as follows:
a) The invention provides automated image adjustment.
b) By virtue of the invention, a certain message is obtained about which side of the mouth is being exposed to obtain an image. This is achieved because the intraoral sensor has to be placed to the mouth the right way up and the orientation sensor provides information, e.g. gravitational vector information, which makes sure which side of the mouth the is being exposed to obtain an image. This is because, if on the right side of the mouth the gravitational vector points to the same direction as the orientation sensor then on the left side of the mouth the gravitational vector has to point to an opposite direction with respect to the orientation sensor.
c) By obtaining a certain message about which side of the mouth has been exposed to obtain the image, and by also using pattern recognition, certain knowledge is provided about which tooth is depicted in each image, thus essentially eliminating possible misinterpretations.